1. Field of the Invention
The present invention relates generally to the field of ophthalmics, more particularly to ophthalmic devices, and still more particularly to ophthalmic devices known as intraocular lenses (IOLs).
2. Background Discussion
An individual's natural crystaline optical lens may become defective, for example, as a result of cataracts or trauma. The current corrective practice is to surgically remove the defective natural lens from the individual's eye (rendering the eye a so-called aphakic eye) and implant into the aphakic eye an artificial lens called an intraocular lens (IOL).
Such IOLs may be constructed of a hard, rigid material, most commonly, an optical grade of polymethyl methacrylate (PMMA). IOLs may alternatively be constructed from an elastically deformable material so they can be rolled or folded for insertion into a patient's eye through a much smaller ocular incision than is required for a rigid IOL. Elastically deformable IOLs are commonly constructed from an optically clear, high refractive index, biocompatible silicone or acrylic material.
IOLs may also be implanted in phakic eyes, that is, eyes still having a usable natural optical crystalline lens. In phakic eyes the implanting of a corrective IOL is an often-attractive alternative for some individuals to wearing corrective spectacles or contact lenses, or having surgical procedures, such as laser sculpting of the cornea, performed.
In an aphakic eye, an IOL is now most commonly implanted in the eye's posterior chamber, in the general location from which the defective natural crystaline lens was previously been removed. In contrast, a corrective IOL for a phakic eye is most commonly implanted in the anterior chamber of the eye, but may sometimes be implanted in the posterior chamber or on top of the natural crystaline lens.
Regardless of the reason for implanting an IOL, or the implant location of the IOL, a principal objective of the invention disclosed in my below-cited patents and of the present application is to provide a dual IOL system in which corrections to spherical, cylindrical and/or add power of a primary IOL can be easily made with minimal invasive action to a patient's eye, by the implanting of a secondary IOL.
Corrective intraocular lens systems are disclosed in my U.S. Pat. No. 6,197,058 B1, issued Mar. 6, 2001, and U.S. Pat. No. 6,537,281 B1, issued Mar. 25, 2003, both of which are incorporated herein in their entirety by specific reference. These prior patents of mine disclose a primary intraocular lens having a narrow recess or groove formed into the anterior surface of the optic adjacent peripheral optic edge regions, and which may extend completely or only partially around the optic. These patents further disclose an elastically deformable, corrective secondary intraocular lens which provides spherical, cylinder and/or add power corrections to the primary intraocular lens, as may, for example, be needed subsequent to the implanting of the primary IOL if the primary IOL has, for any reason, been inaccurately selected or implanted.
The secondary IOL disclosed in the above-cited patents has lens attachment tabs sized to be received into the recess or groove formed in the primary IOL, so that the secondary lens can be detachably attached to the primary intraocular lens. The secondary intraocular lens is disclosed as formed from an elastic material such as a silicone or acrylic material.
Although the corrective IOL systems disclosed in my above-cited patents offer many important advantages, the present invention includes improvements to the disclosed corrective intraocular lens system in the area of improving the detachably attachment of the secondary intraocular lens to the primary intraocular lens.